<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        p {
            height: 100px;
            background-color: black;
        }
        ul li:nth-of-type(1) p {
            background-color: red;
        }
    </style>
</head>
<body>
    <ul>
        <li>
            <p></p>
        </li>
        <li>
            <p></p>
        </li>
        <li>
            <p></p>
        </li>
    </ul>
</body>
</html>